Technologies required to achieve smaller and lighter semiconductor devices include technologies for reducing the size of each embedded component, a System On Chip (SOC) technology for integrating a number of components into one chip, and a System In Package (SIP) technology for integrating a number of devices or chips into one package.
The SIP technology incorporates (or mounts) a plurality of silicon chips vertically or horizontally into one package. The SIP technology is an extension of the Multi-Chip Module (MCM) concept. Manufacturing a package using a horizontal mounting technique may be used for an MCM. A technique for stacking a plurality of chips vertically may be used in the SIP technology.
In a complete system, many passive devices such as resistors, capacitors and inductors are mounted on a system board in association with the characteristics of a plurality of stacked chips and to reduce power input noise. In SIP technology for stacking a plurality of chips, a number of through electrodes for electrical connection and through electrode plugs may be provided between the upper and lower chips. The through electrodes and the through electrode plugs may be formed of a metal such as tungsten (W), copper (Cu), or aluminum (Al). However, if the through electrodes and the through electrode plugs are formed of Cu, reliability may suffer since Cu is easily oxidized when exposed to the air. Oxidation may increase contact resistance.